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<head><meta charset="utf-8"><title>TAIT #86411 · wg-traits · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/index.html">wg-traits</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html">TAIT #86411</a></h3>

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<a name="243563774"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243563774" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243563774">(Jun 22 2021 at 19:02)</a>:</h4>
<p>I know niko would like to move forward on TAIT stabilization as soon as possible, so I thought I'd point out issue <a href="https://github.com/rust-lang/rust/issues/86411">#86411</a> that Matthew opened a few days ago: I hadn't seen it mentioned here yet. Just in case this ICE could be considered a blocker to add to the list.</p>
<p>(It seems it's been present for ever, under the regular TAIT gate, and prior to that with the existential type syntax)</p>



<a name="243564619"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243564619" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243564619">(Jun 22 2021 at 19:08)</a>:</h4>
<p>Thanks <span class="user-mention" data-user-id="116113">@lqd</span></p>



<a name="243567612"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243567612" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243567612">(Jun 22 2021 at 19:32)</a>:</h4>
<p>np :)</p>



<a name="243571386"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243571386" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243571386">(Jun 22 2021 at 20:00)</a>:</h4>
<p>thanks <span class="user-mention" data-user-id="116113">@lqd</span> indeed</p>



<a name="243571472"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243571472" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243571472">(Jun 22 2021 at 20:01)</a>:</h4>
<p>that doesn't seem like a legit use of the type alias</p>



<a name="243571687"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243571687" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243571687">(Jun 22 2021 at 20:02)</a>:</h4>
<p>seems like <a href="https://github.com/rust-lang/rust/issues/76940">#76940</a> fixed the original case but variations managed to slip through this precise check</p>



<a name="243571706"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243571706" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243571706">(Jun 22 2021 at 20:03)</a>:</h4>
<p>Well</p>



<a name="243571717"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243571717" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243571717">(Jun 22 2021 at 20:03)</a>:</h4>
<p>Yes</p>



<a name="243571728"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243571728" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243571728">(Jun 22 2021 at 20:03)</a>:</h4>
<p>But the other thing is that this feels like a "use of an impl trait" that is not a defining use</p>



<a name="243571731"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243571731" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243571731">(Jun 22 2021 at 20:03)</a>:</h4>
<p>so it ought to be illegal with min-alias-impl-trait</p>



<a name="243571751"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/TAIT%20%2386411/near/243571751" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/TAIT.20.2386411.html#243571751">(Jun 22 2021 at 20:03)</a>:</h4>
<p>but I also think it ought to be legal more generally</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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